<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script>
			var array1 = ['a','b','c','e'];
			var array2 = ['d','e','f','f'];
			var b = array1.concat(array2);
			
			for (var i = 0; i < b.length; i++) {
       	 		if (b.indexOf(b[i]) != i) {
          			b.splice(i,1);
           			i--;
        		}
  			}
			document.write(b);
		</script>
	</head>
	<body>
	</body>
</html>
